A side flashing lamp which can be fitted into the cover cap or housing of an external rear view mirror for a motor vehicle can be found for example in U.S. Pat. No. 5,774,283. That side flashing lamp includes a lamp housing with a light exit opening which is closed by a translucent cover. The translucent cover is curved in such a way that, in the installed condition of the side flashing lamp, it extends from the outward end of the cover cap or housing, which is remote from the vehicle, with a continuous transition, into the front side of the cover cap or housing, which faces in the direction of travel of the vehicle. At least one light source is fixedly mounted in the lamp housing and the flashing lamp includes at least one reflector for focusing the light in a main radiation direction which in the installed condition points substantially in the direction of travel of the vehicle. The location at which the side flashing lamp is installed in the cover cap is disposed at the outwardly facing end thereof, remote from the vehicle, while the reflector surrounding the light source which is formed by an incandescent lamp member is arranged in such a way that the main radiation direction extends forwardly with an angle of inclination. The translucent cover is so shaped that it provides for a continuous extension of the external contour of the cover cap. In plan in relation to the position of installation thereof, the translucent cover is curved in such a way that it extends over an angle of about 90.degree., that is to say it faces with its outermost end region approximately transversely with respect to the direction of travel of the vehicle. That configuration is intended to provide that the light which is emitted by the light source when switched on can also be perceived by people who are positioned laterally of the motor vehicle. In order still further to enhance that effect, the reflector is longer in plan on the side which is closer to the vehicle, and is also extended further forwardly, so that it focuses the light which is outputted from the light source in a direction towards the vehicle and reflects it in a focused condition in the opposite lateral direction.
It will be noted however that a disadvantage with the arrangement as outlined above is that it is not possible to provide for rearward radiation of the light produced by the light source, that is to say the light cannot be radiated in the opposite direction to the above-mentioned main radiation direction or the direction of forward travel of the vehicle, so that people who are positioned inclinedly or precisely behind a vehicle fitted with such a side flashing lamp cannot see it.